The present invention relates to a printing method and a printing device.
Information leakage via important printed documents such as confidential communications having been printed on a printing device such as a printer, which is left untended and ends up in the hands of a third-party, has been occurring with increasing frequency. The problem is exacerbated by the difficulty in identifying the source of the leaked printed matter on which information enabling identification of the person who has printed out the document is not superimposed in an indelible format.
The problem is addressed in the invention disclosed in Japanese Laid Open Patent Publication No. 2003-101762 related to a printing method and a printing device achieved by adopting a technology whereby watermark information is superimposed on electronic document data so as to print out the electronic document data by automatically superimposing information indicating the printing party, the printing date or the like (see Japanese Laid Open Patent Publication No. 2003-101762).
However, even the method disclosed in Japanese Laid Open Patent Publication No. 2003-101762 does not provide a complete solution to the problem. Namely, if the terminal at which the printing party issues a printing instruction is located over a considerable distance from the printing device on which the printed matter is output, a third-party may take away the printed matter output on paper before the printing party having issued the printing instruction reaches the printing device. Under such circumstances, it will be difficult to track the printed matter.